CN103312215A - Shaft end overhanging-type piezoelectric beam generator based on clamp limit - Google Patents

Abstract

The invention relates to a piezoelectric beam generator suspended from a shaft end based on clamping and positioning, and belongs to the technical field of new energy and power generation. The left and right end covers are installed on the shell, and the bottom of the end cover is embedded with a limit ring and a bearing; a limit ring and a through-hole hammer are fixed in the shell by screws; Electric vibrator, the other end of the piezoelectric vibrator is clamped between the sharp points of the two limit rings, and a magnet is installed at the free end; the rotating shaft of the rotor is installed on the left and right end covers through bearings, and one end of the rotating shaft is fixed with a connecting plate through a nut; the rotor Magnet 2 is embedded on the turntable. The advantage is that no external fixed support is required; the generator is an integrated independent component, which does not need to change the structure of the rotating body, which is convenient for installation and maintenance; the piezoelectric vibrator is restricted by the limit ring, with high reliability and effective speed bandwidth.

Description

A Piezoelectric Beam Generator Suspended at the Shaft End Based on Clamping and Limitation

technical field

The invention belongs to the technical field of new energy and power generation, and specifically relates to a piezoelectric beam generator suspended from the shaft end based on clamping and limiting, which is used for power supply of a health monitoring system without a fixed support rotating body.

Background technique

In order to meet the power supply requirements of the health monitoring system of rotating bodies such as helicopter propellers, automobile tires, aeroengines, high-speed trains, oil and gas drill spindles and their bearing components, domestic and foreign scholars have proposed various forms of rotary piezoelectric and electromagnetic micro power generation. machine. Relatively speaking, the rotary electromagnetic generator is very mature and has been widely used, but it is not suitable for powering the wireless sensor monitoring system because of the electromagnetic interference generated during the power generation process. In addition, the electromagnetic generator requires a mover Relatively moving with the stator, and the size of the moving/stator is the same, so the structure is complicated and the volume is large, and it cannot or is inconvenient to be used in some small and remote control systems that need to integrate the generator and the rotating body, especially not suitable for automobile tires, cantilever Spindle and other occasions without fixed support. In contrast, the sheet-type piezoelectric vibrator is considered to be an effective method for constructing a micro-rotating generator because of its simple structure, small size, and integration with the rotating body.

According to the excitation method, the early rotary piezoelectric generators mainly include three categories: (1) Inertial excitation type, which uses the change of the direction of force during the rotation of the piezoelectric vibrator to make it bend and deform. This method is simple in structure, but only suitable for At low speed (high speed, especially when rotating at a uniform high speed, alternating bidirectional deformation cannot be produced due to excessive centrifugal force), and sudden changes in the rotation state will cause the piezoelectric vibrator to be damaged due to excessive force/deformation; (ii) toggle (iii) impact type, using rotating and falling steel balls Hitting the piezoelectric vibrator, this method is also only applicable to occasions with low rotational speed, and there is a large impact/noise and possible impact damage. Obviously, the above-mentioned method of exciting along the rotation direction of the rotating body, that is, circumferentially exciting the piezoelectric vibrator to generate electricity has become a technical bottleneck restricting its practical application, and is not suitable for high-speed, uniform speed, and limited space/structure. Therefore, people have proposed new rotary piezoelectric generators based on magnetic coupling excitation, such as Chinese patents 201210319215.0, 201210320165.8, 201210318782.4, 201210318930.2, etc., which have the advantages of no impact and noise, and strong speed adaptability. The effective excitation of the piezoelectric vibrator must be achieved through the relative rotation between the "fixed parts" such as bearing seats or bearing covers and the "rotating body" of the shaft, so it cannot be used for power generation requirements of "no fixed support" rotating bodies, such as rotating wind power generation Machine blades, automobile tires, and various types of overhanging cantilever rotating shafts, etc. In addition, some existing generators use a piezoelectric cantilever structure of equal width, and the diameter of the fixed end is smaller than the diameter of the free end where the magnet is installed, so there will be multiple obvious vibration peaks when excited by the pulse, so that The piezoelectric vibrator has large stress changes, low reliability, and narrow effective speed band during operation; most importantly, if the centrifugal force of the magnet placed on the piezoelectric vibrator is too large at high speed, its axial vibration displacement will be reduced, and even maintain In the equilibrium position, the piezoelectric vibrator will not be able to generate electricity at this time.

Contents of the invention

The invention provides a piezoelectric beam generator suspended from the shaft end based on clamping and limiting, which is a health monitoring system for propellers/vehicle wheels, cantilever shafts and other rotating bodies without fixed support or whose support points are far away from the shaft end. Power supply needs to solve the problems of low power generation efficiency, low reliability, narrow effective speed band, or failure of piezoelectric vibrators to generate power in existing rotary piezoelectric generators.

The technical scheme adopted by the present invention is: the left end cover and the right end cover are respectively installed on the two ends of the shell through screws, and the inner sides of the bottom of the left end cover and the right end cover are respectively inlaid with a limit ring and a bearing; Inside the body, two limit rings and a through hole are provided on the pendent, and the center of the limit ring and the through hole are the same; the left end cover, the right end cover and the shell are respectively crimped with fan-shaped piezoelectric vibrators. The piezoelectric vibrator is made by bonding a metal substrate and a piezoelectric chip. The other end of the piezoelectric vibrator is clamped between the sharp points of the limit ring 1 and the limit ring 2. The free end of the piezoelectric vibrator is installed with a round Shaped magnet one; the rotating shaft of the rotor is installed on the left end cover and the right end cover through bearings, and one end of the rotating shaft is also fixed with a connecting disc through a nut; the rotating disc of the rotor is inlaid with a circular magnet two, and the rotating disc is installed on the The second magnet on it is placed in the through hole of the pendulum; the distance between the second magnet and the first magnet at the end of the piezoelectric vibrator on the left and right sides is the same as the distance from the center of the rotating shaft; The directions are opposite, the polarities of the adjacent magnetic poles of the first magnet at the ends of the piezoelectric vibrator on the left and right sides of the second magnet are opposite, and the magnetic poles of the first magnet placed on the same side of the second magnet are arranged in the same direction.

其中η_n为安装在锤体一，侧压电振子上磁铁一的数量与安装在转盘上磁铁二的数量的最大公约数，

为锤体的中心角，F_y为磁铁二和磁铁一之间产生沿圆周方向的最大作用力，R为磁铁二及磁铁一的中心到转轴中心的距离，R_G为悬锤质心到转轴中心的距离。The gravity of plummet described in the present invention should satisfy:

Wherein η _n is installed on hammer body one, the greatest common divisor of the quantity of magnet one on the side piezoelectric vibrator and the quantity of magnet two installed on the turntable,

is the central angle of the hammer body, F _y is the maximum force along the circumferential direction generated between the second magnet and the first magnet, R is the distance from the center of the second magnet and the first magnet to the center of the rotating shaft, and R _G is the center of mass of the suspended hammer to the center of the rotating shaft distance.

Magnet one and magnet two of the present invention should satisfy following relation: Q ₀ =4arcsin(r/R), among them, μ ₀ is vacuum magnetic permeability, l is the axial distance between magnet 1 and magnet 2 adjacent magnetic poles, L is the axial distance between two magnet 1 adjacent magnetic poles , m ₁ and m ₂ are the magnetic moments of magnet 1 and magnet 2 respectively, λ is a coefficient related to the structure and material parameters of the piezoelectric vibrator, σ ^* is the Xu tensile stress of the piezoelectric material, r and R are magnet 2 respectively Radius and the distance between the magnet and the center of the rotating shaft, _Q0 is the angle between the two centers of two adjacent magnets and the center of the rotating shaft in the circumferential direction of the turntable.

The invention has the advantages of novel structure, (1) the piezoelectric vibrator and its end magnet 1 are kept relatively stationary by utilizing the inertial force of the pendulum, and relatively rotate with the second magnet rotating with the turntable to excite the piezoelectric vibrator to generate electricity, No need for external fixed support; (2) The generator is an integrated independent component, without changing the structure of the rotating body, which is convenient for installation and maintenance; (3) The piezoelectric vibrator is restricted by the limit ring, with high reliability and effective speed bandwidth; (4) The piezoelectric vibrator is arranged symmetrically in the axial direction, and its vibration forces cancel each other out and have no effect on the rotating body.

Description of drawings

Fig. 1 is a structural sectional view of a power generating device in a preferred embodiment of the present invention;

Fig. 2 is the A-A view of Fig. 1;

Fig. 3 is a structural schematic diagram of a pendulum;

Fig. 4 is the left side view of Fig. 3;

Fig. 5 is a comparative diagram of the output voltage-speed characteristic curve of the clamping limit generator and the cantilever beam generator.

Detailed ways

The left end cover 2 and the right end cover 12 are respectively installed on the two ends of the housing 1 by screws, and the inside of the bottom of the left end cover 2 and the right end cover 12 are respectively embedded with a limit ring 4 and a bearing 6; the hammer body 901 of the suspension hammer 9 is screwed Fixed inside the housing 1, two stop rings 902 and a through hole 903 are provided on the pendulum 9, and the centers of the stop rings 902 and the through holes 903 are the same; the left end cover 2 and the right end cover 12 The sector-shaped piezoelectric vibrator 3 is respectively crimped with the housing 1. The piezoelectric vibrator 3 is formed by bonding a metal substrate 301 and a piezoelectric wafer 302. The other end of the piezoelectric vibrator 3 is clamped at a limit position. Between the sharp point of ring one 4 and limit ring two 902, the free end of piezoelectric vibrator 3 is also installed with circular magnet one 5 through screws; the rotating shaft 701 of rotor 7 is installed on the left end cover 2 and the right end cover 12 through bearing 6 Above, one end of the rotating shaft 701 is also fixed with a connection plate 10 through a nut 11; a circular magnet 2 8 is inlaid on the turntable 702 of the rotor 7, and the turntable 702 and the magnet 2 8 installed on it are placed on a suspension. In the through hole 903 of the hammer 9; the magnet 2 8 and the magnet 5 at the end of the piezoelectric vibrator 3 on the left and right sides have the same distance from the center of the rotating shaft 701; The directions are opposite, the polarities of the adjacent magnetic poles of the first magnet 5 at the ends of the piezoelectric vibrator 3 on the left and right sides of the second magnet 8 are opposite, and the magnetic poles of the first magnet 5 placed on the same side of the second magnet 8 are arranged in the same direction.

其中η_n为安装在锤体一侧压电振子上磁铁一的数量与安装在转盘上磁铁二的数量的最大公约数，Q<150°为锤体的中心角，F_y为磁铁二和磁铁一之间产生沿圆周方向的最大作用力，R为磁铁二及磁铁一的中心到转轴中心的距离，R_G为悬锤质心到转轴中心的距离。The gravity of plummet described in the present invention should satisfy:

Among them, η _n is the greatest common divisor of the number of magnet 1 installed on the piezoelectric vibrator on one side of the hammer body and the number of magnet 2 installed on the turntable, Q<150° is the center angle of the hammer body, F _y is the magnet 2 and magnet The maximum force along the circumferential direction is generated between one, R is the distance from the center of magnet two and magnet one to the center of the rotating shaft, and R _G is the distance from the center of mass of the pendulum to the center of the rotating shaft.

Q₀=4arcsin(r/R)，其中，μ₀为真空磁导率，l为磁铁一与磁铁二相邻磁极间的轴向距离，L为两个磁铁一相邻磁极间的轴向距离，m₁、m₂分别为磁铁一及磁铁二的磁矩，λ为与压电振子的结构及材料参数有关的系数，σ^*为压电材料的许拉应力，r、R分别为磁铁二半径及该磁铁到转轴中心间的距离，Q₀为转盘圆周方向上两相邻磁铁二中心与转轴中心连线间的夹角。Magnet one and magnet two of the present invention should satisfy following relation:

Q ₀ =4arcsin(r/R), among them, μ ₀ is vacuum magnetic permeability, l is the axial distance between magnet 1 and magnet 2 adjacent magnetic poles, L is the axial distance between two magnet 1 adjacent magnetic poles , m ₁ and m ₂ are the magnetic moments of magnet 1 and magnet 2 respectively, λ is a coefficient related to the structure and material parameters of the piezoelectric vibrator, σ ^* is the Xu tensile stress of the piezoelectric material, r and R are magnet 2 respectively Radius and the distance between the magnet and the center of the rotating shaft, _Q0 is the angle between the two centers of two adjacent magnets and the center of the rotating shaft in the circumferential direction of the turntable.

During the working process, the connection plate 10 is installed on the end of the rotating body 1 through screws, and drives the rotating disk 702 and the second magnet 8 to rotate together with the rotating body 1 . When the second magnet 8 is close to the first magnet 5 in the circumferential direction, and the two magnets are not overlapped in the circumferential direction, a force F _y along the circumferential direction is generated between the second magnet 8 and the first magnet 5, thereby causing the magnet to The driving torque M _y of the first 5 and the pendulum 9 rotating along the rotating shaft 701, when the second magnet 8 and the first magnet 5 are "tangent" in the circumferential direction, the driving torque is the largest, that is, M _y = RF _y , where R is the second magnet 8 and the distance from the center of the magnet one 5 to the center of the rotating shaft 701; because the center of mass of the suspended hammer 9 is located below the rotating shaft 701 in the initial state, when the suspended hammer 9 turns over a certain angle _Q1 due to the effect of the driving torque M _y , the suspended hammer 9 The gravity G of 9 generates a reverse braking torque M _G =GR _G cosQ ₁ , where R _G is the distance from the center of mass of the plummet 9 to the center of the rotating shaft 701 .

由此得悬锤9的重力应满足:

其中η_n为安装在锤体901一侧压电振子3上的磁铁一5的数量n_a与安装在转盘702上的磁铁二8的数量n_b的最大公约数，Q<150°为锤体901的中心角。In order to ensure that the center of mass of the pendent hammer 9 is always below the center of the rotating shaft ₇₀₁ during the working process of the generator, each magnet two 8 and magnet one 5 should be driven The sum of the torques is less than or equal to the braking torque,

Thus the gravity of the suspension hammer 9 should satisfy:

Among them, η _n is the greatest common divisor of the number n _a of magnets 1 5 installed on the piezoelectric vibrator 3 on one side of the hammer body 901 and the number n _b of magnets 2 8 installed on the turntable 702, and Q<150° is the hammer body 901 Center Corner.

When the pendulum 9 does not rotate with the rotor 7, the piezoelectric vibrator 3 and its end magnet one 5 will rotate relative to the magnet two 8 placed on the turntable 702, changing the overlapping area of the magnet one 5 and the magnet two 8, and Make the force between them change according to the law from small to large, and then from large to small; when the same-sex magnetic poles of magnet one 5 and magnet two 8 are close to each other, repulsive force is generated, and when opposite-sex magnetic poles are close to each other, attractive force is generated. The alternating repulsive force and attractive force between the magnets force the piezoelectric vibrator 3 to produce reciprocating axial bending deformation, thereby converting mechanical energy into electrical energy.

其中:+、-号分别表示吸引力和排斥力，

为磁铁一5与磁铁二8之间的作用力，为两个磁铁一5之间的轴向吸引力，η_S为磁铁一5与单个或两个在转盘702圆周方向相邻的磁铁二8之间的重叠面积与磁铁总面积之比，l为磁铁一5与磁铁二8相邻磁极间的轴向距离，L为两个磁铁一5相邻磁极之间的轴向距离，m₁、m₂分别为磁铁一5及磁铁二8的磁矩，μ₀为真空磁导率。当磁铁一5与磁铁二8中心线重合时，面积比为η_S=1，且磁铁一5所受的吸引力大于排斥力，故压电振子3所受的最大作用力为

为确保压电晶片302在工作中不因承受过大拉应力损毁，应使

其中λ为与压电振子3的结构及材料参数有关的系数，σ^*为压电材料的许用拉应力。During the above working process of the generator, the acting force on the piezoelectric vibrator 3 is the interaction force between the first magnet 5 and the second magnet 8 . Taking the magnet-5 on the left side in Fig. 1 as an example, the total external force suffered by it is:

Among them: +, - signs represent attraction and repulsion respectively,

is the force between magnet one 5 and magnet two 8, Be the axial attractive force between two magnet one 5, η _S is the ratio of the overlapping area between magnet one 5 and single or two adjacent magnet two 8 in the circumferential direction of the rotating disk 702 and the total area of the magnet, and l is The axial distance between the adjacent magnetic poles of magnet 1 5 and magnet 2 8, L is the axial distance between two adjacent magnetic poles of magnet 1 5, m ₁ and m ₂ are the magnetic moments of magnet 1 5 and magnet 2 8 respectively , μ ₀ is the vacuum permeability. When the centerlines of magnet one 5 and magnet two 8 coincide, the area ratio is η _S =1, and the attractive force suffered by magnet one 5 is greater than the repulsive force, so the maximum acting force suffered by piezoelectric vibrator 3 is

In order to ensure that the piezoelectric wafer 302 is not damaged due to excessive tensile stress during work, it should be

Where λ is a coefficient related to the structure and material parameters of the piezoelectric vibrator 3 , and σ ^* is the allowable tensile stress of the piezoelectric material.

In order to generate alternating attractive and repulsive forces between magnet one 5 and magnet two 8, magnet one 5 should not coincide with two adjacent magnet two 8 on the rotating disk 702 in the present invention, that is, two magnets on the rotating disk 702. When one of the adjacent magnet two 8 "cuts out" with the magnet one 5, the other "cuts in", the area ratio at this moment should be η _s =0, so the centers of the two adjacent magnet two 8 and the rotating shaft in the circumferential direction of the rotating disk 702 The included angle between the lines connecting the centers of 701 should be Q ₀ =4arcsin(r/R), where r and R are respectively the radius of the magnet 28 and the distance between the magnet and the center of the rotating shaft 701 . In this working mode, the piezoelectric vibrator 3 is subjected to simple harmonic excitation, so it can only resonate at its natural frequency; on the contrary, for the existing cantilever beam piezoelectric vibrator generator clamped by the infinite ring , in order to avoid mutual adsorption between magnets and damage to the piezoelectric vibrator, only the repulsion method can be used to excite. The excitation method is periodic impact excitation, so the cantilever beam type piezoelectric vibrator is Resonant peaks will appear at any time. Excessive amplitude at resonance may easily cause damage to the piezoelectric vibrator, and at non-resonance, the amplitude and generated voltage may be too low to meet the requirements of use.

In addition, the piezoelectric vibrator 3 in the present invention is clamped by the cusp of the limit ring 1 and the limit ring 2 902, and rotates around the cusp of the limit ring when subjected to an external force. Compared with the piezoelectric vibrator, its bending stiffness and natural frequency are higher, and the axial deformation of the free end is smaller. Therefore, the voltage-speed characteristics of the piezoelectric vibrator in the two different working modes are different, that is, the Vg-n characteristic curves in Figure 5 are different. In Fig. 5, ZL and XL are the voltage characteristic curves of the traditional cantilever beam piezoelectric vibrator and the limited ring piezoelectric vibrator of the present invention respectively. It can be seen from the figure that there are multiple rotating speeds at which the output voltage peaks in the ZL curve. And there is a large difference between the maximum and minimum voltages. When the maximum voltage is too high, the piezoelectric vibrator is likely to be broken due to excessive deformation, and when the minimum voltage is too low, it is difficult to meet the needs of real-time power supply; relatively speaking, the maximum and minimum values of the XL curve The difference in the minimum voltage is small, that is, the stress fluctuation of the piezoelectric vibrator in the entire speed range is small when the limit ring is limited, and the piezoelectric vibrator will not be damaged due to excessive deformation, so the reliability is high and the effective speed bandwidth is high. In the range of 100-900r/min, the voltage values of the XL curve are all greater than the required 5V power supply voltage of the sensor monitoring system, and the voltage of the ZL curve is lower than 5V after the rotating speed is greater than 500r/min, so the limit is adopted in the present invention. Limiting the deformation of the piezoelectric vibrator by the bit ring can effectively improve the reliability and effective speed band width of the piezoelectric vibrator.

In the present invention, the inertial force of the pendulum 9 is used to keep the first magnet 5 installed at the end of the piezoelectric vibrator 3 relatively stationary in the circumferential direction, and generate relative rotation with the second magnet 8 that rotates with the turntable 702 to realize The effective excitation and power generation of the piezoelectric vibrator does not require external fixed support; the generator is an independent component, and there is no need to change the structure of the rotating body during use, and it is easy to install and maintain; the piezoelectric vibrator is restricted by the limit ring, so the generator High reliability and effective bandwidth.

Claims (3)

1. A shaft-end hanging piezoelectric beam generator based on clamping and spacing, characterized in that: the left end cover and the right end cover are respectively installed at the two ends of the housing by screws, and the left and right end cover bottom inner sides are inlaid respectively Limiting ring 1 and bearing; the hammer body is fixed inside the shell by screws, two limiting rings and a through hole are arranged on the pendulum, and the center of the limiting ring and the through hole are the same; the left end cover 1. A fan-shaped piezoelectric vibrator is respectively crimped between the right end cover and the shell. The piezoelectric vibrator is made of a metal substrate and a piezoelectric wafer. The other end of the piezoelectric vibrator is clamped by the limit ring 1 and the limit ring 2. Between the cusps, the free end of the piezoelectric vibrator is installed with a circular magnet through a screw; the rotating shaft is installed on the left end cover and the right end cover through a bearing, and one end of the rotating shaft is also fixed with a connecting plate through a nut; the said The turntable of the rotor is inlaid with a circular magnet 2, and the turntable and the magnet 2 installed on it are placed in the through hole of the pendulum; the magnet 2 and the magnet 1 at the end of the piezoelectric vibrator on the left and right sides are separated from the center of the rotating shaft. The distances are the same; the magnetic poles of the two adjacent magnets located in the circumferential direction of the turntable are arranged in opposite directions, and the polarities of the adjacent magnetic poles of the magnet one at the end of the piezoelectric vibrator on the left and right sides of the magnet two are opposite, and they are placed on the same side of the magnet two The magnetic poles of magnet one are arranged in the same direction. 2. the shaft-end suspension type piezoelectric beam generator based on the clamping limit according to claim 1, is characterized in that: the gravity of the pendent hammer should meet:

Among them, η _n is the greatest common divisor of the number of magnet 1 installed on the piezoelectric vibrator on one side of the hammer body and the number of magnet 2 installed on the turntable, Q<150° is the center angle of the hammer body, F _y is the magnet 2 and magnet The maximum force along the circumferential direction is generated between one, R is the distance from the center of magnet two and magnet one to the center of the rotating shaft, and R _G is the distance from the center of mass of the pendulum to the center of the rotating shaft. 3. the shaft-end hanging type piezoelectric beam generator based on clamping and spacing according to claim 1, is characterized in that: described magnet one and magnet two should satisfy following relation:

Q ₀ =4arcsin(r/R), among them, μ ₀ is vacuum magnetic permeability, l is the axial distance between magnet 1 and magnet 2 adjacent magnetic poles, L is the axial distance between two magnet 1 adjacent magnetic poles , m ₁ and m ₂ are the magnetic moments of magnet 1 and magnet 2 respectively, λ is a coefficient related to the structure and material parameters of the piezoelectric vibrator, σ ^* is the Xu La stress of the piezoelectric material, r and R are magnet 2 respectively Radius and the distance between the magnet and the center of the rotating shaft, _Q0 is the angle between the two centers of two adjacent magnets and the center of the rotating shaft in the circumferential direction of the turntable.

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